Among developers of workstation software, object-oriented programming (or OOP) is increasingly recognized as an important new programming technology. It offers expanded opportunities for software reuse and extensibility, with improved programmer productivity when compared to conventional software development paradigms. Even so, object-oriented technology has not effectively penetrated major commercial software products to date. In particular, operating-systems have hesitated to embrace the new technology.
As with many new programming technologies, the early expressions of OOP concepts focused on the creation of new languages and toolkits, each designed to exploit some particular aspect. So-called pure object-oriented languages, such as Smalltalk, presume a complete run-time environment (sometimes known as a virtual machine) because their semantics represent a major departure from traditional procedurally oriented system architectures. Hybrid languages such as C++, on the other hand, require less run-time support but sometimes result in tight bindings between programs that provide objects and the client programs that use them. Tight binding between object-providing programs and their clients often require client programs to be recompiled whenever simple changes are made in the providing programs. Examples of such systems are found in U.S. Pat. Nos. 4,885,717; 4,953,080 and 4,989,132.
Because different languages and object-oriented toolkits emphasize different aspects of OOP, the utility of the resulting software is frequently limited in scope. A C++ programmer, for example, cannot easily use objects developed in Smalltalk, nor can a Smalltalk programmer make effective use of C++ objects. Objects and classes implemented in one language simply cannot be readily used from another. Unfortunately when this occurs one of the major benefits of OOP, the increased reuse of code, is severely curtailed. Object-oriented language and toolkit boundaries become, in effect, barriers to interoperability.